illphated
The Only Reliable Way to Run untrunc on macOS: Use Docker
If you’re trying to repair a corrupt .mp4 file on macOS and keep running into the dreaded:
nginx
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moov atom not found
…you’ve probably stumbled upon untrunc, an open-source tool that can rebuild broken MP4s using a working reference file. But if you’ve tried installing or building untrunc on macOS, you know the pain — broken repos, missing CMakeLists.txt, or build errors with ffmpeg and clang.
🛑 TL;DR: untrunc doesn’t reliably compile on macOS anymore.
✅ The Reliable Fix? Use Docker
The easiest, cleanest, and most guaranteed way to run untrunc on macOS in 2025 is inside a Docker container.
🧰 Step-by-Step: Run untrunc Using Docker on macOS
1. 📦 Install Docker for Mac
If you haven’t already, install Docker Desktop.
2. 🐳 Create a Dockerfile
Make a folder like untrunc-docker, and create a file called Dockerfile with the following contents:
Dockerfile
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FROM ubuntu:20.04
RUN apt-get update &&
apt-get install -y git cmake g++ ffmpeg
RUN git clone https://github.com/anthwlock/untrunc.git &&
cd untrunc && mkdir build && cd build &&
cmake .. && make
WORKDIR /untrunc/build
ENTRYPOINT [“./untrunc”] 3. 🔨 Build the Image
Open Terminal and run:
bash
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cd path/to/untrunc-docker
docker build -t untrunc .
4. 🏃♂️ Run It
Let’s say your files are in /Users/jamescoder/Videos/untrunc_files/, with:
good.mp4: a working video from the same camera or app
broken.mp4: your corrupted file
Run this:
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docker run -v /Users/jamescoder/Videos/untrunc_files:/files untrunc /files/good.mp4 /files/broken.mp4
If the reference file is compatible, this will produce a repaired MP4 in the same folder.
🎉 Why Docker Is the Best Way
✅ No dealing with brew, clang, or broken CMakeLists.txt
✅ Clean Linux environment with no macOS-specific build issues
✅ Works every time with zero fuss
🔚 Final Thoughts
If you’re on macOS and you’re trying to fix a corrupted .mp4, don’t waste your time fighting local builds. Use Docker and run untrunc the way it was meant to be used — inside a controlled Linux environment.
For more vaporwave-flavored tech guides and digital triage like this, follow me on Twitch.tv/illphated or check out more posts on illphated.com.
🧠 Tags:
#macOS #untrunc #docker #ffmpeg #mp4repair #illphated #linuxhack #moovatom #videofix #twitchtech
Use this too
Docker container
You can use the included Dockerfile to build and execute the package as a container.
The optional argument ‘FF_VER’ will be passed to make.
# docker build –build-arg FF_VER=3.3.9 -t untrunc .
docker build -t untrunc .
docker image prune –filter label=stage=intermediate -f
docker run -v ~/Videos/:/mnt untrunc /mnt/ok.mp4 /mnt/broken.mp4